1. Field of the Invention
The invention relates to devices for aligning articles, and in particular, devices for aligning sheets or the like into edge-aligned stacks.
2. Prior Art
In handling planar articles such as paper sheets outputted from printers, presses, and electrophotographic copiers or the like, it is often required to stack the sheets into aligned stacks for operations such as cutting, stapling and binding. The process of forming stacks of aligned sheets may be done by mechanical means or nonmechanical means.
When sheets are properly aligned with one another by means of the human hands, the process is often referred to as nonmechanical. The partially-aligned stack of sheets is held by the hand, and by tapping adjacent edges of the sheet alternately against a flat surface, forces the sheets into alignment. Although this procedure works satisfactorily, it is not well suited for commercial adaptation. Moreover, the procedure is time-consuming and expensive.
In an attempt to circumvent some of the disadvantages associated with human hands, mechanical devices have been used to align sheets. One type of prior art mechanical aligners consists of an inclined table with a pair of jogger arms pivotally mounted to the table. The jogger arms have a pair of paddle portions extending upwardly above the level of the table along two adjacent sides. The table is inclined towards the paddle portions of the jogger arm. As such, a gravitational force is imparted to the sheets along the direction of the incline. The force helps to bring the sheets into alignment. A driving means consisting of a motor-driven camming system activates the jogger arms which causes pivotal movement of the paddles. The paddles tamp against the sides or edges of the sheets delivered on the table to form a properly aligned stack. A more detailed description of the above prior art joggers as a mechanical aligner is given in U.S. Pat. No. 3,593,992.
Another type of prior art aligners is described in U.S. Pat. No. 3,083,014. In that patent, sheet-like articles to be formed into edge-aligned stacks are delivered to a stacker and jogger mechanism in an overlapped orientation. The stacker and jogger mechanism consists of an alignment surface and a movable table for supporting the articles. Two pair of resilient bladed rotating paddle wheels are mounted; one pair on each side of the table. The paddle wheels in each pair are in spaced relation on its respective side of the table. The paddles are inclined with respect to the table. As sheet-like articles are delivered to the table in the direction of paddle rotation, the rotating resilient paddle wheels contact and lightly impact the opposite edges of the sheets to impart a jogging or vibratory action which aligns the sheet-like articles against the alignment surface.
Although the above-described aligners probably work satisfactory for their intended purpose, there are times when the above aligners do not align the sheets with sufficient accuracy. For example, if some of the sheets in a particular size classification (such as 81/2".times.14" etc.) are slightly undersize, that is, less than the stated size for that classification, the prior art aligners are unable to form a well-aligned stack. The inability of the aligners to accurately align sheets in a stack wherein the dimension of some sheets are slightly less than the stated dimension stems from the fact that the prior art aligners all work on the edges of the sheets. The smaller sheets in a mixed size stack do not extend to the edges of the stack, therefore, tamping on the side of the stack does not always align the sheets since there is no contact between the tamping element and the smaller size sheets.
Also, due to the configuration of the abovereferenced systems, sheets are positively referenced in one direction only. The sheets are driven up to a reference edge perpendicular to the direction of travel. Aligning the sheets in a lateral direction (not the direction of travel) depends on the uniformity and condition of the above-mentioned paddles.